Welding wire feed speed control system method

ABSTRACT

A welding system is disclosed in which the rate of advancement of wire electrode is determined automatically. The device can include a control circuit that determines the rate of advancement of the wire electrode in response to a signal from the voltage selection device of the welding system. Depending upon the operator selected voltage which is selected via the voltage selection device, the control circuit will determine the appropriate rate of wire electrode advancement and control the advancement mechanism (e.g., electric motor) accordingly. Linking of the voltage level and wire-feed speed controls facilities easy of use for more novice operators and, furthermore, facilitates single-handed adjustment of two operational parameters during a welding process.

BACKGROUND

The present invention relates generally to wire-feed welding devicesand, in certain embodiments, to methods and apparatus for controllingwire electrode advancement.

A common metal welding technique employs the heat generated byelectrical arcing to transition a workpiece to a molten state, tofacilitate a welding process. One technique that employs this arcingprinciple is wire-feed welding. At its essence, wire-feed weldinginvolves routing welding current from a power source into an electrodethat is brought into close proximity with the workpiece. When closeenough, current arcs from the electrode to the workpiece, completing acircuit and generating sufficient heat to weld the workpiece. Often, theelectrode is consumed and becomes part of the weld itself. Thus, newwire electrode is advanced, replacing the consumed electrode andmaintaining the welding arc. If the welding device is properly adjusted,the wire-feed advancement and arcing cycle progresses smoothly,providing a good weld.

Traditionally, during a welding operation, an operator selects the leveland types of resources provided to the weld location, depending, ofcourse, on the particulars of the weld and the materials being welded.For instance, an operator may select between various kinds and sizes ofwire electrode, ranging from the diameter of wire the electrode to thematerial the wire electrode is made of. Different kinds of wireelectrode, however, perform well at different operational settings ofthe welding device. That is, different kinds of wire electrodes performwell within different voltage ranges and wire-feed speeds, for instance.For example, a given 0.023 inch mild-steel wire electrode may wellperform at 17 Volts and with a wire-feed speed of 250 inches per minute,while a 0.035 inch mild steel wire electrode well performs at 19 Voltswith a wire-feed speed of 230 inches per minute.

Conventionally, welding devices rely on the knowledge and acumen of theoperator to select the most appropriate voltage and wire feed settingsfor the wire electrode being used and weld conditions. Unfortunately, inmany cases, the weld operator is a novice to field, especially in thecase of portable welding devices. If the operator does not properlyadjust the voltage and wire-feed speed settings, the arcing may not besufficient to produce a good weld, or a weld at all. Furthermore, intraditional devices, the wire-feed speed control and the voltage controlare wholly independent from one another, thus making it difficult forthe operator to adjust the both parameters while a weld is progressing.

Therefore, there exists a need for improved apparatus and methods forthe control of wire-feed welding devices.

BRIEF DESCRIPTION

In accordance with one embodiment, the present technique provides awelding system in which the rate of advancement of wire electrode isdetermined automatically. For example, the device can include a controlcircuit that determines the rate of advancement of the wire electrode inresponse to a signal from the voltage selection device of the weldingsystem. Thus, depending upon the operator selected voltage—which isselected via a voltage selection device—the control circuit willdetermine the appropriate rate of wire electrode advancement and controlthe advancement mechanism (e.g., electric motor) accordingly.Advantageously, linking the voltage level and wire-feed speed controlsfacilities easy of use for more novice operators and, furthermore,facilitates single-handed adjustment of two operational parametersduring a welding process, for instance.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagrammatic representation of a wire-feed welding system,in accordance with an exemplary embodiment of the present technique;

FIG. 2 is a schematic representation of a wire-feed welding systemcontrol, in accordance with an exemplary embodiment of the presenttechnique; and

FIG. 3 is a diagrammatic representation of a wire-feed welding systemcontrol, in accordance with an exemplary embodiment of the presenttechnique; and

FIG. 4 is a diagrammatic representation of a wire-feed welding systemcontrol panel, in accordance with an exemplary embodiment of the presenttechnique.

DETAILED DESCRIPTION

As discussed in detail below, the present technique, in accordance withcertain embodiments, provides method and apparatus for controlling theadvancement of wire electrode in a welding device. For example, ametal-inert-gas (MIG) welding system incorporating the present techniquecan include an “AUTO” setting that links the wire-feed speed to thevoltage-level or vice-versa. Thus, in such a system, if an operator wereto adjust the voltage to the wire electrode, the wire-feed speed wouldbe automatically adjusted to accommodate the new voltage setting.Alternatively, the selected wire-feed speed can automatically determinean output voltage level. Advantageously, the linked relationship betweenthe voltage-level control and the wire-feed control can assist anoperator in obtaining desirable performance and, furthermore, canfacilitate multifunctional control of the welding device via a singleinput knob. FIG. 1 illustrates an exemplary welding system that includesan embodiment of this wire-feed control technique. Indeed, the system 10may be for portable use, and such systems are often stationed byless-experienced operators. However, prior to continuing, it is worthnoting that the following discussion merely relates to exemplaryembodiments of the present technique. Thus, the appended claims shouldnot be viewed as limited to those embodiments described herein.

Returning to the exemplary welding system 10, it includes a weldingtorch 12 that defines the location of the welding operation with respectto a workpiece 14. Placement of the welding torch 12 at a locationproximate to the workpiece 14 allows electrical current provided by apower source 16—which converts incoming alternating current (ac) powerto an appropriate direct current (dc) power—and routed to the weldingtorch 12 via a welding torch cable 18, to arc from the welding torch 12to the workpiece 14. In summary, this arcing completes an electricalcircuit from the power source 16, to the welding torch 12 via thewelding torch cable 18, to a wire electrode, to the workpiece 14, and,at its conclusion, back to the power source 16, generally to ground.Advantageously, this arcing generates a relatively large amount of heatcausing the workpiece 14 and/or filler metal to transition to a moltenstate, facilitating the weld.

To produce electrical arcing, the exemplary system 10 includes awire-feeder 20 that provides a consumable wire electrode to the weldingtorch cable 18 and, in turn, to the welding torch 12. The welding torch12 conducts electrical current to the wire electrode via a contact tip(not shown) located in the neck assembly, leading to arcing between theegressing wire electrode and the workpiece 14.

To shield the weld area from contaminants during welding, to enhance arcperformance, and to improve the resulting weld, the exemplary system 10includes a gas source 22 that feeds an inert, shielding gas to thewelding torch 12 via the welding torch cable 18. It is worth noting,however, that a variety of shielding materials, including various fluidsand particulate solids, may be employed to protect the weld location.Additionally, certain wire electrodes are designed to operate without ashielding material.

Advancement of these welding resources (e.g., welding current,wire-electrode, and shielding gas) is effectuated by actuation of atrigger 24 secured to a handle 26. By depressing the trigger 24 (arrow28), a switch disposed within the trigger 24 is closed, causing thetransmission of an electrical signal that commands promotion of thewelding resources into the welding torch cable 18. For example,depressing the trigger 24 sends a signal to the control circuitry 30,which, in turn, activates a motor 32 that advances wire electrode intothe welding torch cable 18, opens a valve to allow the flow of shieldingmaterial, and commands the power source to output the desired level ofpower to the wire electrode. Advantageously, the control circuitry 30includes memory components 34, to store programming instructions,command programs, appropriate data, etc. The control circuitry 30 alsoincludes a processing device, such as a processor 36, a programminglogic circuit (PLC), among others types of devices, to effectuatecontrol of the welding system 10.

To adjust operating parameters of the welding system 10, a pair of inputdevices are provided: a wire-feed speed controller 38 and a voltagecontroller 40. As illustrated, these input devices are potentiometerdevices (i.e., POTS); however, other kinds of input devices, such askeypads, are envisaged. Each POT controller comprises a knob 42 that ispositionable between indexed locations that correspond with certainoperational parameters. For example, in the illustrated welding system10, the power source 16 outputs power within the operational range often to forty volts. An operator can control the output voltage to thewire electrode by turning the knob 42 on the voltage controller 40between the indexed positions, which are labeled from “1” to “7”. If avoltage closer to 40 V is desired, the knob 42 can be turned toward the“7” position. Conversely, if less output voltage is desired, the knob 42on the voltage controller 40 can be turned toward the “1” position.Similarly, the wire-feed speed of the system 10 can be adjusted byrotating the knob 42 of the wire-feed speed controller 38 between the“3” and “7” positions, with the “3” position being a lowest operatingwire-feed speed (e.g., 75 inches per minute) and “7” being the fastest(e.g., 1400 inches per minute).

When left in a manual mode, the operator relies on his or her weldingacumen to select the appropriate voltage-level and wire-feed speedsettings, based on the type of weld to be made, the kind and size of thewire electrode, among other relevant factors. Many operators, however,may not have the breadth of experience and knowledge generallybeneficial to make such decisions. Resultantly, maladjustment of thewelding system 10 is possible. For example, if the wire-feed speedsetting is too slow in comparison to the voltage level setting, then anarc may not form or may extinguish prematurely. Conversely, if thewire-feed speed setting is too fast for the given voltage level setting,then the quality of the weld may be reduced. Additionally, when thesystem is in a manual mode, an operator may benefit from adjustments inthe voltage setting, which, in turn, benefits from adjustments in thewire-feed speed setting. Unfortunately, in a manual mode, the operatormay find it difficult to maintain the arc by depressing the trigger 24while concurrently manipulating both the wire-feed speed controller 38and the voltage controller 40.

To alleviate such concerns, the exemplary welding system 10 includes an“AUTO” setting 44 on the wire-feed speed controller 38. As illustratedin FIG. 2, placement of the wire-feed speed controller 38 at the “AUTO”setting 44 transitions the welding system 10 from a manual mode to amore automated mode. For example, by selecting the “AUTO” setting 44,the control circuitry 30 automatically links the voltage level settingand the wire-feed speed setting, automatically adjusting the wire-feedspeed setting based on the selected voltage level setting. Asillustrated, when the voltage controller 40 is placed at the “4”location, the control circuitry 30, in cooperation with its processor 36and data stored in the memory 34, determines the appropriate wire-feedspeed setting, in this case the wire-feed setting corresponding to avoltage level setting of “4.” This correlation can be made via the useof a look-up table 46 stored in the memory 34, or can be made via theuse of an appropriate algorithm, among various other techniques forcorrelation.

Also, the “AUTO” setting may be found on the voltage control, the systemdetermining a wire-feed speed based on selected voltage level.

During operation, the operator may determine that a more appropriatevoltage setting is desired, adjusting the voltage controller 40 settingto the “3” position, for instance. In turn, the control circuitry 30will determine the appropriate wire-feed speed setting—based on thelook-up table 46 or a stored algorithm, for example—and instruct towire-feed motor 32 to operate at this designated speed. Advantageously,the operator can adjust both the wire-feed speed and voltage levelparameters through the manipulation of a single knob 42 on the voltagecontroller 40.

Turning to FIG. 3, this figure represents a wire-feed speed controlscheme for a voltage controller 40 essentially having an infinite numberof voltage settings between the “1” and “7” positions. With thiscontroller 40, an operator may select from an essentially infinitenumber of voltage settings in the operational range of the weldingsystem 10 simply by slightly adjusting or “tweaking” the position of theknob 42. However, the wire-feed speed setting, when the controller 38 isin the “AUTO” position, is automatically selected based on the range ofvalues the voltage controller 40 is within. For example, the illustratedvoltage controller 40 is set at a position slightly beyond the midpointbetween the “3” and “4” settings. At this voltage setting, the controlcircuitry 30 determines that the wire-feed speed setting correspondingto a voltage setting of “4”, which may be gleaned from the look-up table46, is to be applied. In fact, as illustrated, the control circuitry 30commands the wire-feed motor 32 to operate at the wire-feed speedcorresponding to a voltage level setting of “4” if the voltage controlis set at or beyond the mid-point between the “3” and “4” settings, andat or before the mid-point between the “4” and “5” settings. Thiswire-feed speed setting scheme can be, of course, extended to the othervoltage settings. For instance, the wire-feed speed setting for thevoltage level setting of “4” may be applied when the voltage controller40 is set at a location at or beyond the “4” setting but at or beforethe “5” setting. Alternatively, and by way of example, the wire-feedspeed setting may be based on an algorithm, thus providing anautomatically determined wire-feed speed essentially for each possiblevoltage setting between the “1” and “7” positions.

FIG. 4 represents yet another alternative, exemplary mechanism forcoupled control of the wire-feed speed and voltage level. Asillustrated, the “AUTO” setting on the wire-feed speed controller 42 issegregated into two sub-sections, each for a different kind or size ofwelding wire. By way of example, one sub-section corresponds to a mildsteel wire electrode having a diameter of 0.030 inches and the othercorresponds to a mild steel wire electrode having a diameter of 0.024inches, for example. It is, however, worth noting that the “AUTO”section can be divided into any number of sub-section, eachcorresponding to a different type or size of wire electrode. Dependingupon the sub-section selected, the advancement rate of the wireelectrode for a given voltage setting is changed. For example, if thewire-feed speed controller 42 is placed at the “0.030” setting, thecontrol circuitry 30 will select from a first look-up table thatcorresponds with the 0.30 inch wire electrode to determine the wire-feedspeed for the given voltage setting. Moreover, as the voltage setting ischanged, the control circuit will remain within the first look-up table,selecting the wire-feed speed corresponding to the newly selectedvoltage. However, if the wire-feed speed controller is placed at the“0.024” setting, the control circuitry 30 will look to a second,different look-up table to select the wire-feed setting for the givenvoltage setting. Moreover, as the voltage setting is changed, thecontrol circuitry 30 will remain within this second look-up table,selecting the wire-feed speed corresponding to the newly selectedvoltage. Thus, the operator can automate the wire-feed setting selectionto best suit the type of wire electrode employed. Of course, thewire-feed speed, rather than being selected from a look-up table, can bedetermined based on an appropriate algorithm, each algorithmcorresponding to the type and kind of wire electrode employed, amongother techniques. Where desired, a further input device may be providedfor selecting which wire size or electrode type is being used. Incertain implementations, the same input device may provide multiplepositions or selection settings, certain of them corresponding tospecific sizes or types of electrodes.

As a further alternative, an input device that functions along with orin place of knob 40 may be employed directly on the welding torch. Forexample, an adjustment knob or button (e.g., a rocker switch) might beprovided on the handle of the welding torch itself. Where desired, asignal then is taken from a conductor extending to the switch that isinterpreted by the controller. The effect of the signal may be toincrease and decrease the applied voltage, with wire feed speed beingcontrolled as a function of the voltage, or vice versa. Such anarrangement would permit adjustments to the voltage and wire feed speedto be made while a welder is working remotely from the base unit, suchas at the position of a workpiece or work area, without interrupting thework to return to the base unit.

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

The invention claimed is:
 1. A welding system, comprising: a powersource configured to output power within a range of power levels; anadvancement mechanism configured to advance wire electrode into awelding torch of the welding system at a rate of advancement; a firstinput device operable to select the rate of advancement; a controlcircuit configured to determine an output level of the power sourcebased on the selected rate of advancement; and a second input deviceoperable to manually select the output power level and to at leastpartially disable the control circuit.
 2. The welding system of claim 1,wherein the control circuit determines a single output power level for arange of inputs from the first input device.
 3. The welding system ofclaim 1, wherein the first input device is provided on the weldingtorch.
 4. The welding system of claim 1, wherein the power source, thefirst input device, the second input device, the advancement mechanism,the control circuit, and the power source are disposed in a singlehousing.
 5. The welding system of claim 1, wherein the control circuitcomprises a processing device and a memory component in communicationwith the processing device, the memory circuit storing data correlatingoutput power levels with rates of advancement for wire electrodes. 6.The welding system of claim 1, wherein the control circuit is configuredto determine a first output level of the power source based on firstparameter data of a first wire electrode and the rate of advancement,and to determine a second output level of the power source based on asecond parameter data of a second wire electrode and the rate ofadvancement, wherein the first and second wire electrodes are differentfrom one another.
 7. The welding system of claim 1, wherein the secondinput device comprises a user control that includes an automatic settingand a plurality of output power levels.
 8. The welding system of claim7, wherein the user control comprises a knob having the automaticsetting and the plurality of output power levels at different angularpositions about the knob.